Malignant gliomas are a heterogenous group of neoplasms that remain refractory to treatment in the majority of patients. To further our understanding of the molecular alterations associated with abnormalities of glioma growth control, this project will utilize Flow Cytometry (FCM) to analyze two separate aspects of glioma biology, first in cultured cells and then in resected tumor specimens: 1) mutation of p53; and 2) expression of p-glycoprotein, glutathione S-transferase, and DNA Topoisomerase II. Flow cytometry allows for characterization of these tumors on an individual cell by cell basis, so that specific subpopulations can be detected which have different molecular pathogenetic mechanisms. p53 is a tumor suppressor gene that, when mutated, produces a protein involved in the transformation process of gliomas. Utilizing indirect fluorescein isothiocyanate (FITC) immunostaining, we will estimate the expression of mutant p53 and correlate its relative fluorescence to tumor type and grade, ploidy, cell cycle parameters, and patient survival. Alterations in expression of P- glycoprotein, glutathione S-transferase, and DNA Topoisomerase II by tumor cells are implicated in de novo and acquired tumor chemoresistance. To establish our methods, we will initially estimate the relative amounts of these compounds in several continuous cultured glioma cell lines using indirect FITC immunostaining for p-glycoprotein, glutathione S-transferase, and DNA Topoisomerase II. Experiments will then be conducted in tissue culture systems to demonstrate that FCM measurement of these compounds correlates with resistance to etoposide, alkylating agents, and vincristine. FCM measurements of p-glycoprotein, glutathione S- transferase, and DNA Topoisomerase II will then be correlated with tumor type and grade, ploidy, and cell cycle parameters, time between diagnosis and recurrence, and patient survival. Results of these studies should lead to understanding of the molecular abnormalities responsible for: a) abnormal growth control in these tumor cells; b) the inability of current therapy to control the growth of many human gliomas.